Tankless coil for baseboards on steam boiler lost water

hadeone

Hi all, we had a cold couple of days and I ran the basement baseboards about 24 hours.  I have a steam weil mclain eg45 with a tankless coil attachment that runs the basement baseboards only.  It seems like the loop sprung a leak somewhere because I woke up to banging pipes and 0 pressure. Turns out  I had my feed valve off for the loop.  I never had to add water in the last 3 years since i’ve been here so I never touched it.  

I filled the loop up and kept the thermostat off for the baseboards overnight, feed valve off still, and this morning the pressure went down to a bit over 10, valve is for 15psi. The boiler was running for steam but the tankless thermostat was off.  So im guessing there is a leak somewhere now. 

I can live without this loop until spring when I was planning to replace the tankless coil because its also leaking around the plate. 

My question is can I drain the loop and have the tankless coil sit in the boiler without water?  Im not sure where its leaking from and Id rather not have it drip into the house somewhere.  

Thank you

Long Beach Ed

You can drain the loop and the coil, but if the leak is in the coil, boiler water will get back into it.

hadeone

Thanks.  I dont see any obvious leaks in the basement, by the radiators, but most of the piping is behind sheetrock.  Ill keep looking.  

I guess the banging in the pipes was due to whatever water was left in the pipes turned to steam? If boiler water gets into the loop after i drain it ill know because ill get some banging ? 

I just want to make sure i dont damage anything in the boiler by leaving this coil empty.  

Thanks again

Long Beach Ed

If the leak is in the coil and it worsens, the boiler water level can be affected. But you have a low water cut-off that should protect the boiler in that case.

hadeone

I have a ball valve right before the pump that brings water into the coil, then after the coil theres an auto bleeder, expansion tank and flow check valve, then the pressure and temp gauge.  

The auto feed valve feeds into the “hot” side after the pressure gauge, and im keeping the ball valve from the fresh water suppY closed until i can find the leak.

Am I correct thinking that if I close the valve the coil is isolated by the valve and the check valve?  That way the pressure gauge will only gauge the rest of the circuit. Therefore if it drops then Ill know to look for a leak throughout the basement?